1. Field of Invention
This invention relates generally to a charging apparatus for an electric vehicle, and more particularly to an automated charging system for docking and charging an electric vehicle.
2. Description of Related Art
With concerns over pollution rising, there has been greater interest in the use of electric powered vehicles for passenger transportation. While limitations such as charging capacity and vehicle speed had previously made large scale implementation of electric vehicles unworkable, advances in technologies such as storage cell design, braking regeneration, and motor efficiency have made electric vehicles a viable alternative to vehicles powered by internal combustion engines. However, one major limitation to the full scale implementation of electric vehicle fleets remains: providing a safe, effective means for recharging the storage devices of electric vehicles.
For example, the power storage capacity of an electric vehicle has been improved to the point where electric vehicles now have ranges similar to that of combustion engine powered vehicles. However, while the fuel cell of a combustion engine (i.e. gas tank) can be refueled at locations like service stations in ten minutes or less, "refueling" an electric storage cell may take several hours. Therefore, it is more likely that consumers will perform the bulk of their recharging needs overnight while the vehicle is parked in their garage or during the work day while the vehicle is parked in the parking lot at work.
To date, most electric vehicle charging systems involve the connection of a power cable between the vehicle and a charging tower or station. This presents several disadvantages. First, the power cord must be provided either at the charging station or be carried with the vehicle. If the cord is provided at the power station, there is risk that the cord may become damaged due to improper use by the many different people who would utilize the charging station. The cord may become frayed, or the plug connectors damaged due to misuse or abuse. Likewise, if the cord is to be carried with the vehicle, repeated use and abuse of the cable can cause damage. Also, the driver may forget the cable, or it could be stolen from the vehicle. Whether the power cable is associated with the vehicle or the charging station, severe damage to the cable and charging connectors on the vehicle and charging station could result if the vehicle is driven away with the cord still engaged. Likewise, the power cable connecters may be damaged by accidentally driving a vehicle wheel over the power cable connector.
Also, by requiring the vehicle driver to establish the power cable connection between the vehicle and the charging station, risk of personal injury is increased. A careless or inexperienced user may accidentally short across the power terminals. Inclement weather such as rain and snow increase the risk that the charging circuit may be accidentally shorted while connecting the system. Also, there is the risk that the user may connect the polarity of the charging system incorrectly, or that the user will fail to observe proper safety procedures such as waiting until the connection is fully established before activating the power generation system.
Other contingencies pose challenges as well. For example, different types of vehicles will likely require different charging voltages and will have different charge storage capacities. Therefore, the user may be confronted with having to select the proper type of charging station and charging cord to meet his vehicle's charging requirements. Or, the user may be required to manually set the charging station to deliver the proper total charge and charging rate to his vehicle. Obviously, the chances that an inexperienced or careless user would deliver improper charging rates to his vehicle's charging system increases the likelihood that the system will be damaged and therefore require repair.
Finally, because most known methods of connecting a charging system to an electric storage cell necessitates some form of connector having a relatively higher degree of resistance than found in the other portions of the charging circuit, the charging connector becomes hot, risking injury to the user and increasing the risk that surrounding combustible materials may ignite.
It would therefore be advantageous to provide an electric vehicle charging system which does not require the user to manually establish a connection between the vehicle and the charging station. Such a system should be capable of automatically ensuring that the correct charging rate and total charge is delivered to the vehicle to prevent overcharging of the vehicle's storage system. The charging system should also be capable of ensuring a good connection is made between the charging station and the electric vehicle to ensure the vehicle is indeed being charged. Furthermore, the system should prevent the delivery of charging power from the charging station until this connection is established, to reduce the risk of injury due to shock and risk of damage to the charging circuitry. Finally, it would be beneficial if such a system were universal, such that any variety of vehicles could be charged from a single charging station, obviating the need for special adapters.